Synthesis of novel boron containing unnatural cyclic amino acids as potential therapeutic agents

Two boronated α-amino acids, 1-amino-3-boronocyclopentanecarboxylic acid and 1-amino-3-boronocycloheptanecarboxylic acid were prepared. The key step in the syntheses was the 1,4-boration of the α,β-unsaturated cyclic ketones using the bis-pinacolatodiboron ester to generate the boronated ketones which were then converted to the corresponding amino acids.